Is it still at 13%? We're a ways past February...take a look at the smart list for the send and see if they differ greatly.
You can see all of the changes in their releases here: https://community.marketo.com/MarketoArticle?id=kA050000000LIVJCA4 -- but I'm nearly positive nothing they have done would cause issues with email deliverability.
Are you saying that the February newsletter had an open rate of 19% and then a different one you've sent since then has an open rate of 13%?
If it was the same newsletter, it's not uncommon to start out higher and then the numbers normalize a bit after all the emails have been delivered. I would take a look at a larger swathe of your newsletters and get more of an average to compare it against.
Take a look at what Matt suggests. Also look if your email changed or the list has changed in some way.
Have your subject lines changed?
Do an AB test to see what happens as well.
Check your delivered % too.
Thank you guys. Matt, that release info is good to know, thanks. I will take a look at other things that probably caused the decline. We have been sending that newsletter for years and that one month we seemed to dip and not recover. I'm sure that there are other issues but I was asked to check the tech side of Marketo.
Thanks for the help!
With our previous newsletter and current blog emails, I saw an open rate of 25% in the beginning, and months later it went down to anywhere from 20 to 15%. Part of the reason was a big chunk of our subscribers' emails became invalid. We were also told by some of our customers that we were sending too many emails which was true. Our promotional emails were competing with our other subscription emails. Changing our email delivery days, times and frequency helped.